As a fluid controller, a diaphragm valve is known, which comprises a valve body having a flow channel where fluid flows, a diaphragm which opens/closes the flow channel by abutting against and separating from the flow channel, a bonnet which sandwiches a circumferential edge of the diaphragm between the bonnet and the valve body, and an operation mechanism for moving up and down the diaphragm.
By way of an example of such traditional diaphragm valves, a diaphragm valve, for example, having structures shown in the following Patent Document 1 is known.
In this diaphragm valve, a circumferential edge (A) of a square diaphragm is sandwiched between a flange part (B) provided at an upper part of the valve body and a flange part (C) provided at a lower part of the bonnet and then fastened by a bolt (D) and a nut (E), so that the diaphragm, the bonnet, and the valve body are fixed, as shown in FIG. 11.
However, the diaphragm valve having such structures needs to be fastened and fixed with four bolts and nuts, and requires some time to be assembled and disassembled. Therefore, it has poor working efficiency with regard to manufacture and maintenance.
Furthermore, there is a problem that the diaphragm valve is required to increases its size and weight, since a flange part needs to be provided to sandwich the diaphragm between the valve body and the bonnet.
On the other hand, Patent Document 2 as shown below discloses a diaphragm valve having a clamp-type fixing structure for fixing a valve body and a bonnet using a clamping member.
However, the disclosed prior art has the problem as described below.
The disclosed prior art needs a circular diaphragm in a planar view, because it needs to use a clamp-type fixing structure. Therefore, the disclosed prior art has the problem that the diaphragm unfavorably rotates when assembling etc. and thus it can be hardly arranged at a given position (rotation angle) in an easy and accurate way. Especially, in case of exchanging diaphragms of valves attached to a place with poor workability (narrow space for manufacture lines etc.), it is difficult to accurately position and attach a diaphragm due to difficulty in visual confirmation.